In recent years, there has been a demand for improved performance in various aspects of magnetic recording and reproducing apparatuses and enhanced functions thereof in conjunction with the increased demand for such apparatuses including VTR's. Particularly in the case of VTR's, the control of tape tension and improvement in its control characteristics have been major tasks necessitated by the desire to ensure that a magnetic head is provided with optimum head touch.
A known form of tape tension-controlling device has a tape tension-detecting pin disposed at a tip portion thereof and is equipped with a tension-detecting arm which is displaced with the center of a tension arm acting as a supporting center in response to variations in the tape tension experienced by a magnetic tape, thereby controlling tape tension at the time when the magnetic tape wound in a cassette is loaded onto a rotary cylinder via a tape guide.
The tape tension-detecting pin of this tension-detecting arm abuts against the magnetic surface side of the magnetic tape. However, since the magnetic tape cannot be wound sufficiently in the process of a loading-operation, i.e., since the magnetic tape cannot retain a sufficient winding angle with respect to the tape tension-detecting pin, the tension-detecting pin cannot sensitively read variations in tape tension. Thus, no consideration has been given to providing sufficient tape tension-controlling characteristics, i.e., to the fact that a control effect cannot be sufficiently obtained with respect to increased tension (tension drift) from the start to the end of tape winding on reels (refer to the official gazette of Japanese Patent Laid-Open No. 86161/1982).
In addition, for instance, in the case of an upward loading of a tape onto the entrance side of the rotary cylinder, or in a case where the tape tension varies and the tape tension-detecting pin consequently moves to the left and the right, there is a possibility of tape contact with a cassette wall proximate to a tape draw-out port of the cassette, thereby causing damage to the magnetic tape, unless a post for restricting the tape-traveling position is provided at a portion of the tape tension-detecting pin adjacent to the cassette in the traveling direction of the tape.